Emulsion compositions containing active compounds are known in the art. For example, WO 91/02517 published Mar. 7, 1991 discloses an oil-in-water emulsion of a drug which is poorly soluble in water. Said drug is dissolved in a solution of high or low pH to facilitate dissolution. Said acidic or basic drug-containing solution is added to a pre-formed emulsion which itself contains an acid, base, or buffer to neutralize the emulsion once the active solution is added.
Emulsion products containing actives subject to hydrolysis may be negatively effected during processing or storage from acidic or basic conditions created during processing of such products. Aside from the use of acids and bases to make the product, the acidic or basic character of the emulsion products is also attributable to the raw materials comprising the emulsion. For example the final emulsion product can be more or less acidic depending on the source of the water used. Furthermore, acidic or basic conditions can be created when the final emulsion product is pH balanced with an acid or base. Therefore, there is a need for the development of emulsion compositions and processes for making said emulsion compositions which are uneffected by the acidic or basic conditions found during production and even storage of such products.
It is therefore an objective in the present invention to create emulsion compositions comprising active compounds subject to acid or base hydrolysis having improved efficacy and product aesthetics. It is a further objective of the present invention to provide a process for making said emulsion compositions. Another object of the present invention is to make skin care products used in regimens of men and women, including products containing skin lightening actives to lighten basal skin tone and hyperpigmented lesions.